>>8661110 (LB)

Here is the difference between a natural earth quake and an underground explosion:

https://mainichi.jp/english/articles/20160106/p2a/00m/0na/011000c

Notice that natural EQs have a sort of "pre-rumble", whereas explosions happen suddenly.

The EQs you were looking at LB all have that pre-rumble. They're natural EQs